1. Field of the Invention
The present invention relates generally to an image forming apparatus and, more particularly, to a system and method for sensing a media stack from a side of the stack and a side of a delivery path to the stack in order to detect a given stack height and thus when an output bin of the image forming apparatus is full.
2. Description of the Related Art
Traditional output bin sensing systems in image forming apparatus, such as electrophotographic printers, use a mechanical flag and sensor mechanism to sense when the height of a media stack reaches a predetermined level. When this happens, the system will generate output signals indicating the output bin is full and instruct the user to remove the media stack before proceeding with additional jobs. This system typically includes a mechanical flag type arm that acts on the top of the media stack in the output bin. An example of such a system is disclosed in U.S. Pat. No. 6,279,889 assigned to the assignee of the present invention.
Many printers are architected in a reverse “C” format where the media sheet exits in the back of the printer and away from the user. An example of such a printer is disclosed in U.S. Pat. No. 7,292,820 assigned to the assignee of the present invention. The traditional output bin full sensing system has a couple of drawbacks related to the human factors involved in using the output bin of these printers. First, the mechanical flag functions on the top of the media stack where it can impede the user in easily removing the stack from the output bin and pulling it towards the front of the printer. Second, if the media stack is replaced by the user into the output bin, the media stack can easily trap the mechanical flag in way that prevents the mechanical flag from functioning properly and thereby potentially leads to unintended media jams. These issues can lead to even worse human factors issues in an All-In-One (AIO) device where a scanner is positioned above the media stack.
Thus, there is a need for an innovation which will satisfactorily overcome the aforementioned drawbacks of the traditional output bin full sensing system without introducing any significant new drawbacks in place thereof.